In recent years, as can be seen in the introduction of labeling systems and the like, there has been a demand to reduce the rolling resistance of pneumatic tire. Techniques for reducing rolling resistance include securing the proper air pressure by suppressing decreases in internal tire pressure over time, and reducing the tire weight.
The suppression of decreases in internal tire pressure can be achieved by increasing the thickness of the innerliner so as to enhance the air permeation prevention performance, but the tire weight increases as a result. When the tire weight increases, the rolling resistance becomes poor.
Japanese Unexamined Patent Application Publication No. 2009-138135A proposes enhancing air permeation resistance and reducing rolling resistance with a rubber composition for an innerliner containing mica having an average particle size of from 25 to 100 μm and an aspect ratio of from 25 to 100.
However, inorganic fillers such as mica have a large specific gravity, so there is a problem in that the tire weight and rolling resistance increase. When the innerliner is made thin in order to suppress increases in tire weight, there is a problem in that the air permeation prevention performance decreases or the tire durability decreases. Therefore, a pneumatic tire that achieves good air permeation prevention performance, good durability, and reduced tire weight in a compatible manner has not yet been established.